You will receive a delivery report for every Viber message you send.
Below is a breakdown of the possible delivery statuses and what each one means:
1. Not Sent
The Viber message failed to reach the recipient.
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No Credits (Account): The account does not have enough balance to send messages.
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Invalid MSISDN: The phone number is not valid.
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Invalid URL: The URL included in the message is not valid.
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Restricted SMS (Anti-SPAM): An anti-spam filter was triggered, which prevents sending the same message multiple times to the same recipient within a short time frame.
2. Failed
The Viber message was not delivered due to one of the following reasons:
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Unknown User:
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The recipient does not have the Viber app installed.
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The recipient has opted not to receive messages from businesses.
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The recipient has blocked the specific Viber Sender ID.
These last two settings can be managed by the user in the Viber application.
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SMS Failover (IM Unknown User):
In Viber campaigns with SMS failover enabled, this status means the recipient could not receive the Viber message (due to one of the reasons above), and the message was instead sent via SMS.
3. Succeeded
The message was delivered successfully.
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Delivered:
The message has been successfully delivered. Note that users can disable the "Seen" status in Viber settings, so a message may remain in "Delivered" status even if it has been read. -
Seen:
The recipient received and opened/read the message.
4. Undelivered
The message failed to reach the destination.
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Expired:
The allowed delivery window expired before the message could be delivered. -
Sent:
The message has been sent, but delivery is still pending. This may occur if the recipient’s device is turned off or offline. The provider will continue trying to deliver the message.